真的可以当个健康的胖子？答案没那么简单（而且有争议）

2013年，一项研究成果对公认的核心健康原则提出了质疑，即超重并不一定不健康？看起来似乎有悖常理，但这正是此项研究的结果。通过对已有成果综合分析，该研究发现比起BMI（身体质量指数）处于健康水平的研究对象,介于25到30（高于合理范围）的人们过早死亡可能性反而更低。

约七成美国成年人都超重或肥胖。有赘肉可能不一定代表健康亮红灯，在某些情况下可能还是长寿的标志。这项发现堪称突破，立即成为头条新闻，随后风靡互联网，引出一大批讲述“胖但健康”的故事和轶闻。

该项研究还引发了营养学家之间的激烈论战（《大西洋月刊》对这场大战做过精彩总结）。简而言之，对2013年研究的批评集中在没有考虑研究对象以往的体重情况，也就是说以前肥胖后因疾病减重的人被列入了体重健康人士行列，从而人为夸大了正常体重人群过早死亡的风险（同时降低了超重者过早死亡的风险）。

排除上述影响因素后，随后的一系列研究不仅未能发现超重有益健康，还得出了截然相反的结论，那就是超重幅度越大，死于心血管疾病或某些癌症的风险就越高（公平地说，确实也有些后续研究发现了超重和健康的正向关系）。此外，认为超重不利于健康的营养学家对之前研究者的方法提出了批评（基本观点：这些都是观察性研究，必然包含诸多参数，想得出清晰而又可复制的结论极为困难）。

这并未妨碍研究者收集更多数据。而且就是在这样的背景下，他们又针对体重与健康的关系进行了一次新的研究，并且明确断言超重并不健康。

此次研究的报告发表在《欧洲心脏杂志》杂志上，研究者对50多万人进行了逾10年的跟踪。在此期间，约7500人患了心脏病。在研究之初处于超重或肥胖状态明显提高了研究对象患心脏病的可能性。关键在于，研究伊始新陈代谢处于健康状态的超重者或肥胖者，或者说血压、血糖和血脂指标都很正常的胖子患病几率同样提升。排除了多种因素（包括饮食、饮酒、健身活动和社会-经济状况）的影响后，新陈代谢健康的超重者和肥胖者患心脏病的几率比新陈代谢数据正常且BMI处在正常范围的人分别高26%和28%。

帝国理工学院公共健康分院流行病学家卡蜜尔·拉萨尔是这篇研究报告的作者之一。她说，这些发现表明，肥胖会提高出现健康并发症的风险。她的猜想是，对新陈代谢健康的超重者来说，额外体重对健康的影响只是暂时没出现而已。拉萨尔指出：“根本没有‘健康的胖子’。健康专业人士应该建议超重病人改变生活方式，让体重回到正常水平。”

她知道这些话可能不太中听。越来越多的研究显示，减肥会改变身体的新陈代谢情况，从而使大幅减重极其困难，维持体重的则容易得多。拉萨尔承认：“大多数情况下减肥都会失败。体重下降后也很难维持。”

她的另一项建议有点儿扎心，那就是从社会角度而言，我们也许首先应该把注意别让子女超重或肥胖上（起码以后他们不用为了健康BMI而辛苦减肥）。

不过，拉萨尔希望被上述研究结果吓了一跳的人们保持理性。没错，这项研究发现超重会提高得心脏病的风险。但相关报道同样掩盖了另一个更重要（可能更符合事实，但很难上头条）的真相，那就是如果想更健康，多运动，饮食要更均衡多样，多摄入植物蛋白，少吃添加糖份、饱和脂肪以及加工食品吧。

没错，这样就有可能减肥成功，而且有可能同时提高新陈代谢健康水平，也是患心脏病几率的最重要指标，体重只是其中一项。（财富中文网）

译者：Charlie

审校：夏林

In 2013, a study came out that questioned a core health principle: what if being overweight, on its own, wasn’t actually unhealthy? As counterintuitive as it seemed, that’s what the new research suggested. A meta-analysis of existing studies, it found that participants with a BMI of 25 to 30 (above the optimal range) were less likely to prematurely die than those with a healthy BMI.

Around 70% of the U.S. adult population is either overweight or obese. The possibility that carrying around extra pounds wasn’t necessarily a red flag—that, in some cases, it could actually be a mark of longevity—was groundbreaking. The study immediately made headlines. From there, it rippled through the Internet, inspiring a slew of stories and anecdotes on the benefits of being “fat but fit.”

It also inspired a fiery debate among nutrition scientists. (The Atlantic has an excellent summary of the drama.) In short: the main criticism of the 2013 study was that it failed to account for participants' weight history, which meant previously heavy people who lost weight due to illness were put in the “healthy weight” bucket, artificially inflating the risk of premature death for normal-weight people (while artificially decreasing it for their overweight peers).

After controlling for the above, a series of subsequent studies not only failed to find a protective benefit from being overweight, but actually found the opposite: the more an individual exceeds a healthy weight, the higher his or her risk of mortality from cardiovascular disease and certain cancers. (To be fair, other subsequent studies have found a protective relationship.) For many of these papers, nutrition scientists on the opposite side of the debate attacked the researcher’s methodology. (Bottom line: these are all observational studies that must contend with range of variables, which makes drawing clear-cut, replicable conclusions extremely difficult.)

This hasn't stopped researchers from trying to refine their collection techniques. And so against this backdrop comes a new study on weight and health, one that comes decisively down on the side that carrying around extra pounds is unhealthy.

Published in the European Heart Journal, researchers tracked more than half a million people for over a decade. During that period, around 7,500 developed heart disease. Being overweight or obese at the start of the study significantly increased participants’ likelihood of falling into that camp. Importantly, this link remained even for those who were overweight or obese but metabolically healthy at the beginning of the study, i.e. they had healthy blood pressure, blood sugar, and cholesterol readings. After controlling for a variety of factors (including diet, alcohol intake, physical activity, and socio-economic status) these metabolically healthy overweight and obese individuals were a respective 26% and 28% more likely to develop heart disease than participants with similar readings and a healthy BMI.

The findings suggest obesity, in itself, increases the risk of developing health complications down the road, says Camille Lassale, an epidemiologist from Imperial College London's School of Public Health (and one of the study’s authors). Her hypothesis is that for those who are overweight but metabolically healthy, the health impact of those extra pounds simply hasn't caught up with them yet. “There is no such thing as 'fit but fat,'” she says. “Health professionals should advise patients who carry extra weight to make lifestyle changes in order to return to a normal weight range.”

She understands that this isn’t easy news to hear. A growing body of research suggests losing weight alters the body’s metabolism, making it incredibly difficult to achieve, much less maintain, significant weight loss. “Most interventions aren’t successful,” she concedes. “Weight loss rarely lasts.”

Lassale’s next suggestion is a bit heartbreaking: as a society, perhaps we should focus on ensuring our children never become overweight and obese in the first place (and thus locked in a struggle with their metabolisms to achieve a healthy BMI).

Still, for anyone alarmed by the findings, Lassale urges a return to common sense. Yes, the study found that being overweight is linked with a higher risk of developing heart disease. But the corresponding coverage also mask a larger (if more consistent, and less headline-friendly) truth: for those looking to improve their health, focus on moving more and developing eating patterns that are balanced, full of variety, rich in plant-protein, and low in added sugars, saturated fats, and processed foods.

Yes, you could lose weight. But aside from that, you’ll likely improve your metabolic health, the most important indicator of subsequent heart disease, and of which weight is but one factor.